1. Field of the Invention
The present invention relates to a technology of controlling the temperature of an object to be heated by using radiation heat generated from a radiation heating means.
2. Description of the Background Art
An object to be heated (such, as glass substrate) and vacuum treated for forming a film thereon has been conventionally heated by a sheath heater attached in an object-to-be-heated placement table contacting the object during the treatment or a preliminary heating before the treatment. In this case, the temperature of the object to be heated is controlled, with the temperature of the object-to-be-heated placement table having been measured in a heating chamber, with the use of a program that controls the output of the heater based on the temperature of the placement table, a target temperature for heating, and a target time until such time as a target heating temperature is reached.
However, when the object to be heated contacts the placement table equipped with the sheath heater as a transmission heating means, particles may be generated due to friction between the surface of the heater and the glass substrate, or a film adhered to the surface of the heater may be peeled off during the treatment, which likely results in contamination of the product thereby causing deterioration of the production yield.
In addition, there has been a need for the heating treatment time to be shorter than in the past.
In this respect, a radiation heating means (such as, a lamp heater) can, in principle, raise the temperature of the object to be heated in a short heating time without contacting the object to be heated by means of radiation heating (see, Japanese Patent Document mentioned below).
In order to prevent heat loss through heat conduction from the object to be heated while the absorption rate of infrared rays on the object to be heated is enhanced in treatment apparatuses using such radiation heating means, instead of the use of the placement table for the conduction heating by means of the sheath heater, a vertical-substrate treatment apparatus in which the substrate is held by a carrier and both the carrier and the substrate are made to stand in the apparatus supports a glass substrate as the object to be heated by the carrier, while a horizontal-substrate treatment apparatus which treats a substrate with its horizontal posture held therein makes use of a pin having a minimized contact area with the object to be heated; and both the horizontal-substrate treatment apparatus and the vertical-substrate treatment apparatus have difficulties in measuring the heat by means of conventional temperature measuring mechanisms with only a glass substrate, as the object to be heated, being fixed inside the apparatus.
For the above reason, the temperature of the object to be heated has been controlled, with the temperature of a temperature measuring plate made of the same glass material as that of the glass substrate, which is the object to be heated, being measured, with the use of a program that controls the output of the heater based on the temperature of the temperature measuring plate, a target temperature for heating, and a target time until such a time as the target heating temperature is reached.
However, with the use of the conventional temperature measuring plate and the program, when the output of the radiation heating means is increased in order to increase the temperature rise rate of the glass substrate, accurate monitoring of the temperature-rise of the glass substrate cannot be attained due to a slow response of the temperature measuring plate, thereby causing a problem of overheating the glass substrate.
See, Japanese Patent Document JP-B 4071047.